1. Field of the Invention
The present invention generally relates to contact members and connectors including the contact members. More specifically, the present invention relates to a contact member used when an LGA type or a BGA type IC package is mounted on a circuit board and a connector including the contact member.
2. Description of the Related Art
Integrated Circuit (IC) package connectors have been used in order to mount LGA (Land Grid Array) type or BGA (Ball Grid Array) type IC packages on circuit boards where the LGA type or BGA type IC packages can be easily exchanged. Recently, high reliability, large amounts, and high speed of data transmission have been required for such IC package connectors.
As transmission speed of data becomes higher, it is necessary to consider the influence of inductance of contacts. In recent years, the transmission speeds of the data are of GHz order of magnitude. In order to properly transmit the data, it is required that the inductance of the contacts of the IC package connector be of nanohenry (nH) order of magnitude.
In addition, the contact is required to have a structure where an elastic force is generated when the contact is used. Furthermore, it is also required that the size of the contact be small so that the contact can correspond to pitches of pads of the IC package.
FIGS. 1(A) and 1(B) are views showing an example of a related art contact member. More specifically, FIG. 1(A) is a top view and FIG. 1(B) is a side view.
As shown in FIGS. 1(A) and 1(B), a contact member 1 has a structure of a helical spiral spring having plural turns. See, for example, Japanese Patent Application Publications No. 56-8837, No. 2001-235486, and No. 2005-129428. The contact member 1 is used where the contact member 1 is compressed in an axial direction so that a repulsion force is generated. The transmission path of an electrical signal is helical.
Although the contact member 1 shown in FIGS. 1(A) and 1(B) has an elastic force, inductance of the contact member 1 is not small because the transmission path of the electrical signal is helical. Accordingly, the contact member 1 shown in FIGS. 1(A) and 1(B) may not be proper for high speed data transmission.
In addition, the size of the contact member 1 shown in FIGS. 1(A) and 1(B) is not small. Hence, the contact member 1 may not be proper as a contact member of, for example, an IC package connector which is required to be arranged with a short pitch.